Catalysis



Patented June 13, 1944 UNITED STATES PATENT OFFICE' 2,351,562 ce'mnrsrs Preston L. Veltman, Fishkill, N. Y., assignor, by mesne assignments, to The Texas Company, New York, N. Y., a corporation of Delaware No Drawing. Application May 2, 1941, I 7 Serial No. 391,482

This invention relates to a catalyst for the conversion of hydrocarbons and particularly for effecting molecular transformation of petroleum hydrocarbons.

Broadly, the invention contemplates a catalyst comprising a, metallic halide containing two or more different halogen atoms, namely, fluorine, chlorine, bromine or iodine, combined with one metal in the same molecule, and which will be defined herein as amixed metallic halide. Examples of such catalysts comprise aluminum dichloro fluoride, aluminum chloro difiuoride, aluminum chloro pentafiuoride, (AlzClFs) and mixtures of molecules of this nature. Hydrogen halide, boron halide or alkyl halides may be used as a promoter for the mixed metallic halide catalyst.

The invention contemplates the employment of a catalyst comprising a mixed metallic halide of the foregoing type or a mixture of two or moreof these mixed metallic halides for eil'ecting contion.

the employment of the foregoing type of catalyst for effecting isomerization ofstraight chain hydrocarbons to produce branched chain hydrocarbons.

- The mixed halides of this invention, including hydrated forms thereof, may be employed alone or in combination with other catalytic agents or with suitablecarrier or supporting materials, or

may be dissolved or dispersed in suitable liquid media. Thus, these mixed metallic halides may be employed in conjunction with simple metallic halides of the type AlCla, SbClz, etc. Examples of suitable carriers comprise natural or artificial clays, such as aluminum silicates and fullers earth. Other materials include silica, alumina, diatomaceous earth; bauxites, aluminum phosphate and the like, including mixtures thereof. Suitable liquid media would include inorganic salts of relatively low melting point, such as BbCla and SbFs, metallic organic compounds, and organic compounds capable of carrying the catalyst in suspension or in solution. Certain metallic halide-hydrocarbon complexes may also serve ascarriers for the catalysts described herein such as the complex often formed during the isomerization, of hydrocarbons with metallic halides.

Also it is contemplated that the catalyst may beused in a finely powdered form suspended in a stream of hydrocarbon vapor or gas undergoing treatment by contact with the suspended catalyst. r

It is already known to employ a metallic halide,

such as aluminum chloride, as a catalyst for effecting cracking, isomerization, polymerization and alkylation of hydrocarbons. Aluminum chloride, promoted with hydrogen chloride, is an ef-' tem where vaporized-hydrocarbons are being treated with the catalyst in solid form.

A complex metallic halide, such as fluorinated aluminum chloride, as contemplated by the pres--v ent invention, provides a catalyst which is superior to ordinary aluminum chloride with respect to resistance to sludging and subliming tendencies. It is less soluble in mineral oil and also requires a higher temperature for sublima- A quantity of aluminum chloro-fluoride cata-' lyst was prepared by subjecting anhydrous alumihum chloride vapors at the sublimation temperature at atmospheric pressure to intimate contact with boron trifluoride in a glass tube so as to form a mixed aluminum chloro-fluoride salt and boron trichloride. The aluminum chloride and boron'trifluoride were charged to the reaction in the proportion of 261.5 parts by we ght of anhydrous aluminum chloride to 55 parts of I boron trifiuoride, the resulting solid product amounting to 228.5 parts by weight. These proportions can be changed so as to vary the amount of fluorine substituted for chlorine in the original aluminum chloride. The amount of boron trifluoride added was somewhat in excess of that I in a trap cooled in a bath comprising a mixture of dry ice and kerosene.

The solid product finally obtained had a greywhite appearance, sublimed at a much higher 2 temperature than aluminum chloride, dissolved slowly in water, and apparently is substantially insoluble in paraflinic hydrocarbons and allryl halides. Its chemical analysis corresponds approximately to a mixed halide having a stoichicmetric formula of 'AlClzF, and is substantially free from boron and boron halides. The chemical reaction forming this catalyst apparently involves a process of double decomposition as indi-.

cated by the following equations: 7 a

' 3A1Clz+BFs- 3AlClaF+BCl: 3a1c1m+nrs+aa1c1ra+nc1= '1 etc.

Mixed metallic halides can be prepared by simple partial replacement reactions using ele-, mental halogens. The ability to displace one another from salts decreases in the order of fluorine, chlorine, bromine and iodine. That is fluorine can displace chlorine, bromine and iodine, while chlorine can displace only bromine and iodine. Bromine can displace iodine only. By suitable selecti on of salts and control of the conditions under which the reaction is eifected substantially any halogen ratio can be obtained in a single salt.

It is contemplated that many non-metallic fluorine compounds can be used as a source of fluorine. Hydrogen fluoride, silicon tetrafluoride and organic fluorides react, at moderate temperatures, with metal salts, such as aluminum chloride, to give aluminum chloro fluoride which comprises one of the types of catalysts contemplated herein.

A sample of this catalyst was employed as an isomerization and cracking catalyst in which .nor-

.mal pentane was subjected to conversion by contact with the catalyst at a relatively low tem-' perature. In this experiment 1224 parts of 5 free from boron, containing not more than about normal pentane, 135.1 parts of catalyst and 5.9

5 The hydrocarbon product was subjected to a low temperature fractional distillation, obtaining the following fractions and yields thereof, expresser as mol per cent:

Moi per cent Hydrocarbons boiling below isobutane 0.1 Isobutane 53.0 n-Butane 4.1 Isopentane 20.5 n-Pentane 5.4

Hydrocarbons boiling above n-pentane um. 16.3 The foregoing analysis demonstrates that the catalyst is highly active for catalyzing either iso-.-

merization or cracking reactions.

. 'In another example a mixed halide catalyst was prepared by reacting aluminum chloride and boron trifluoride at atemperature o! 230 to 235 F. 'The reaction was eflected in a heated cylindrical reaction tower through which powdered by means of a conveyor screw. Boron trifluoride was passed through the tower concurrently with the aluminum chloride in the proportion oi. approximately 136 parts by weight of boron trifluoride to 450 parts by weight of aluminum chloride over a period of about minutes.

The resulting catalyst contained 47.9% chlorine and 33.2% fluorine and was substantially 0.06% boron by weight. It was in the form of a finely divided grey powder.

A quantity ofthis catalyst was used to isomerize normal pentane at a temperature of F. in a batch liquid phase operation, the time of reaction being four hours. The quantity of catalyst charged to the reactor amounted to 10% by weight of the normal pentane. The reactionwas carried out without the addition of any promoter. The hydrocarbon reaction product obtained had, the following composition: I

Per-cent Isobutane 4.6 n-Butane 1.9 Isopentane .4. 62.4 n-Pentane 26.8 Residue 4.3

Thus, the reaction product contained 62.4% isopentane and in addition examination of the catalyst indicated the absence of any complex formation, the catalyst being unchanged in physical appearance.

Another sample of aluminum chlorofluoride catalyst (containing 58% fluorine) was used to isomerize n-butane in batch liquid phase at 250 F, Ten per cent of catalyst and 2% 1101, by weight, based on total charge to the reactor, were charged to the system. A four hour reaction period was used and the hydrocarbon reaction product obtained had the following composition:

. Per cent Hydrocarbons below C4 1.5

Isobutane 60.8

n-Butane 34.1

Hydrocarbons heavier than C. 3.6

The catalyst was recovered as a light 'dry powder apparently unchanged. vThere was no evi-y dence of complex formation.

While a mixed halide of aluminum has been described above, it isnevertheless contemplated that mixed halides of other metals capable of combining with two or more halogen atoms may 0 be used. Polyvalent metals in groups 2, 3, 4,5.

and 6 of the periodic table including iron, cobalt,

lightly or heavily fluorinated. It may have an empirical formula such as MeHkH", where x and 11 have values suiiicient to satisfy the valency halide compounds of two -or more diflerent metals.

Although batch liquid phase experiments have been described above it is contemplated employing the catalyst in continuous flow operations and in ith 11 phase aluminum chloride of about 100 mesh-was forced m 8 er mud or vapor treatment ture'of the hydrocarbon feed to betreated. Rir

75 example, in isom'erizing a iced hydrocarbon conrelatively 2,351,562. sistingessentially of normal butane a temperature in the range 180 to 300 F. may be employed, but preferably a temperature of about 210 to 250 F. If the feed consists essentially of normal pentane the temperature employed may be in the range 100 to 250 F. and preferably about 130 F. The optimum temperature, of course, would depend upon the contact time used for any particular hydrocarbon or mixture of hydrocarbons charged to the isomerizing unit.

Also while specific procedures for preparing the catalyst have been described, it is contemplated that these procedures may be varied and that other methods may be employed. L

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A method of isomerizing straight chain paraflin hydrocarbons which comprisessubjecting .said hydrocarbons to contact with an active catalyst comprising a metallic mixed halide containing at least two different halogen atoms in the same molecule, said halide being substantially free from boron and boron-halides, and efiecting said contact under isomerizing conditions in the presence or hydrogen halide such that substantial conversion to branched chain hydrocarbons is secured.

2. A method of isomerizing straight chain paraflin hydrocarbons which comprises subjecting said hydrocarbons to contact with an active catalyst comprisingas the sole active isomerizing agent a metallic mixed halide containing at least two different halogen atoms in the same molecule, having the approximate empirical formula Mefl xlvy, where Me signifies a metal, H and H signify diflerent halogen atoms and z and 1! have values suflicient to satisfy the valency of the metal, and eflecting said contact under isomerizing conditions in the presence of hydrogen halide such that. substantial conversion to branched chain hydrocarbons is secured.

3. A method of isomerizing straight chain paraffln hydrocarbons which comprises subjecting said hydrocarbons to contact-with an active catalyst comprising as the sole active isomer-icing two diil'erent halogen atoms in the same molecule, and connected tothe some metal atom, and effecting said contact under isomerizing conditions in the. presence of hydrogen halide such that substantial conversion to branched chain hydrocarbons is secured. v

4. A method or isomerizing a hydrocarbon feed consisting mainly of normal pentane which comprises subjecting the feed hydrocarbon to contact with an active catalyst comprising as the sole active isomerizing agents aluminum mixed halide containing chlorine and fluorine atoms in the same molecule,- and eifecting the contact agent a metallic mixed halide containing at least under isomerizing conditions in the presence of hydrogen halide at a. temperature in the range of about to 250 F. such that substantial conversion to isopentane is secured.

5. A method of isomerlzlng a hydrocarbon feed consisting essentially of normal butane which comprises subjecting the feed hydrocarbon to contact with an active catalyst comprising as the sole active isomerizing agent aluminum mixed halide containing chlorine and fluorine atoms in the same molecule, and effecting the contact under isomerizing conditions in the presence of hydrogen halide and at a temperature in the range 180 to 300 F. such that substantial conversion to isobutane is secured.

6. A method of converting straight-chain paraflln saturated hydrocarbon which comprises subjecting the feedhydrocarbon to the action of a catalyst comprising a metallic mixed halide containing at least two different halogen atoms in the same molecule, having the approximate empirical formula Mefl xfl y, where Me signifies a metal, H and H signify different halogen atoms and a: and 11 have values sumcient to satisi'y the valency of the metal, said catalyst being substantially free from boron and boron halides, and effecting contact between the feed hydrocarbon and said catalyst under isomerizing conditions such that conversion of feed hydrocarbons into isomers having the same number of carbon atoms per molecule constitutes the principal reaction.

'7. The method according to claim 6 in which the catalyst comprises a mixed halide of aluminum.

8. A method of isomerizing saturated hydrocarbons which comprises subjecting said hydrocarbons to contact with a catalyst in which the sole active isomerizing agent is a metallic mixed halide containing at least two diiferent halogen atoms in the same molecule, and connected to the same metal atom, and eflecting said contact at a temperature in the range 180 to 300 F. in the presence of hydrogen halide such that substantial conversion to isomers is secured.

9. A method of isomerizing saturated hydrocarbons which comprises subjecting the saturated hydrocarbons to contact with a solid catalyst formed by reacting, aluminum chloride with boron triiiuoride at the sublimation temperature for aluminum chloride under conditions of reaction so as to form a yellow crystalline intermediate reaction product, and subjecting said intermediate product to continued heating to convert it into a relatively stable solid or greyish appearance and consisting essentially of aluminum chlorfluorlde having the approximate empirical formula AlClzFy, where a: and u have values sumcient to satisfy the valency of the aluminum, and eflecting said contact under isomerizlng conditions in the presence of hydrogen halide such that substantial conversion to isomers is secured.

PRESTON L. VEL'IMAN. 

